Reenforced-concrete stairs



Feb. 10, 1925.

C. W. DONALDSON RBENFORCED CONCRETE STAIRS Filed Ma rch 2e 1920ATTORNEYS raamea Feb. 10, 1925.

cHARLnsW. DONALDSON, or CHICAGO, ILLINOIS.

- REEN'FORCED-CON CRETE STAIRS.

Application filed. March 26, 1920.

To all whom it may concern Be it known that I, CHARLES IV. DONALD- soN,citizen of the United States, residing at Chicago, in the county of Cookand State of Illinois, have invented certain new and useful Improvementsin Reenforced-Con crete Stairs, of which the following is aspecification.

This invention has to do with the erection of reenforced concretebuilding units, and deals especially with the problemofconstructingunits of this class in the form of stairs susceptible ofbeing built of metallic reenforcing and concrete or cement mortarwithout necessitating the employment of forms such as are ordinarilyrequired for thepurpose under the conditions of common practice to-day.

The invention may be said to comprise not only a complete reenforcedconcrete stairs of the type mentioned, but also in cludes what may becharacterized as a stairs form unit constituting an article ofmanufacture. It is adapted to be set up as apart of either concrete orwood building construction and availed of for making stairs ofreenforced concrete.

In the practice of my invention I utilize, preferably metal lath forforming the side stringers of the stairs and for forming the metalreenforcing shape for making the risers and treads, the former beingsuitably connected with the stringers as a preliminary, of course, tothe final application of concrete or cement mortar, allowed in duecourse to set in order to form the final complete structure.-

Secondary to the foregoing I employ preferably ribbed metal lath as areenforcing material and reenforcing form, the ribs being employed in aspecial way, both for the stringers, treads and risers, to obtain a mostadvantageous construction.

Included in my invention is a special construction of intermediatestringer designed for use for wide stairs, though susceptible of beingemployed as a side stringer if such might be desired.

Owing to the capacity of the metal lath reenforcing used by me to beshaped into different forms, this material affords unusuallyadvantageous facilities for erecting stairs of curved or other shapes,the material being adapted to be bent accordingly.

Serial No. 368,972.

Vhere my stairs are used in concrete COIlj structions involving walls ofreenforced concrete the metal lath or reenforcing shaped to make therisers and treads may be connected to the wall construction to thusafford a unitary or monolithic wall and stairs of advantageousconstruction, all of which will be appreciated more fully in connectionwith the following description, and on reference to the accompanyingdrawings, in which:

Figure 1 illustrates the assemblage of the metal lath forming the risersand treads, and a side stringer, in longitudinal section.

Figure 2 is a. similar view, but showing the application of the cementmortar or concrete to the metallic reenforcing as in the completedconstruction.

Figure 3 is a transverse section through the parts shown in Figure I.

Figure 4 is a View similar to Figure 1, but enlarged to more fullydisclose the construction and illustrate a modification.

Figure 5 is a side view, broken away, of a stringer such as may be used,preferably midway of the side stringers of the stairs, if side stringersare employed, as in wide stair construction.

Figure 6 is a view showing in perspective, and partly broken away a walland stairs such as constructed in accordance with this invention, thelowermost stair being bullnosed if desired.

In my system of construction the stairs are of such a simple nature asto possess especial merit for this reason alone. lVhere the stairs aremade with a form-unit construction, as I shall term it, I employ thespaced longitudinal stringers A intermediate the stairs proper whichcomprise the treads 1 and the risers 2. The stringers A are made ofribbed lath of suitable lengths joined together to provide a unitcomprising the number of steps required in the particular construction.Any reenforcing lat h of metal of the various types being produced todaymight be employed, however. The spread lath provides an advantageouslath reenforcing shown after a manner at a, and the ribs designated 6forming the reenforcing elements lengthwise of the stringer, in anobvious manner.

The risers and treads are made by bending the lath of which they arecomprised into the desired form and the ribs of the risers and treads,designated 3, constitute the transverse reenforcing elements for thestructure, in their relation to the stringers A.

The risers and treads as a unit are connected with the stringers A bywire ties or any similar fastening means, shown best at 4 in Figure 3.The complete reenforced stairs unit is made by applying cement mortar orany suitable cementitious product to the form unit provided by thestructure shown in Figure 1. Preferably the stairs section including therisers and treads will be covered by the cement mortar both above andbelow. Thereafter the cement mortar will be applied to the stringers A.In this way the mortar applied tothe stringers forms shoulders beneaththe steps proper. This, however, would be true whether the mortar isapplied to the stringers first, or to the risers and treads, though thefirst described method will be found best in practice.

Figure 4 shows how reenforcing rods 5 may be readily applied to both thestringers A and the risers and treads, to increase the rigidity of theform unit preliminary to the application of cement mortar, when desired.

Middle stringers and, should it be desired, even side stringers may bemade by the construction shown in Figure 5, wherein b designates thereenforcing ribs of metal lath and a the cut out sections of the up perpairs of lath, cut out to conform with the riser and tread sections ofthe completed stairs construction.

In Figure 6 I show a concrete wall. construction at B, and the stairs Care also illustrated, the lowermost one of the stairs being bull-nosedas previously described. Now, if the wall B be made by the applicationof cement mortar or concrete to the metal lath, obviously said wall lathmay be employed as the stringer section for my stairs C, the risers andtreads reenforcing material designated 2 and 1, respectively, beingattached directly to the wall lath section.

The foregoing will indicate how readily adaptable my construction is tothe erection of stairs not only for concrete, but also for woodenbuildings, and simplicity and cheapness characterize my invention, fromthe building standpoint, in many different 1'1, spects. Of greatimportance, too, is the doing away with the need of temporary woodenforms for the purposes of construction.

Having thus described my invention, what I claim as new is:

1. A stair construction including a perforate sheet of reinforcementbent to form risers and treads, a stringer reinforcement associated withthe first mentioned reinforcement and also formed of perforate material,and a cementitious body applied to opposite sides of the. riser andtread and stringer reinforcements and flowing through the perforationsthereof to provide a. bond between the layers of cementitious material,so that the cementitious material can be applied without a form, thereinforcements being embedded in the cementitious body to provide amonolithic riser and tread and stringer construction.

2. A stair construction including a perforate sheet of reinforcementbent to form risers and treads, a stringer reinforcement associatedtherewith, supplemental reinforcements extending longtudinally of therisers and treads and stringer reinforcement, and a cementitious bodyapplied to opposite sides of the reinforcements and flowing through theperforations thereof to bond the two layers of cementitious material sothat they can be applied without a form, the reinforcements beingembedded in the cementitious body, and a monolithic riser and tread andstringer construction being formed.

3. A monolithic stair unit including a sheet of metal lath bent to formrisers and treads, a stringer reinforcement connected with the risersand treads, and a cementitious body applied to both sides of the risersand treads and stringer reinforcement so as to completely embed the sameand providing a monolithic riser and tread and stringer unit.

4. Reenforced concrete stairs comprising a sheet of reinforcing materialbent to form risers and treads, a stringer reinforcement of metal lat-hassociated with the risers and treads and having an edge portion thereofcut out to conform thereto, and a cementitious body applied to oppositesides of the reinforcements and embedding the same to provide amonolithic riser and tread and stringer construction in wh ch thestringer reinforces the stairs on one side thereof without projectingbeyond the risers and treads on the other side thereof.

In testimony whereof I aflix my signature.

CHARLES w. DONALDSON.

